[DOC] update doc

[Remi-Gau]

• closes Ensure examples in doc can actually build #568
• switch to using the latest distro / software versions in examples
• try to only show examples that are known to build
• comment out section of the doc that are not relevant given the build failure status of some softwares
• test the build of some of the examples
• leave out nipype example out of the doc until fixed

[codecov]

Codecov Report

Patch has no changes to coverable lines.

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[kaczmarj]

thanks very much!! this will help us catch regressions and make sure we don't confuse our users with broken tutorials :)

[Remi-Gau]

am afraid the nipype tuto build will stay FUBAR for a little while
also I think it assumed that SPM would work with octave which is not something neurodocker supports anymore, right?

[Remi-Gau]

Not sure what to do about the nipype example: getting this one to work won't be that easy

[Remi-Gau]

tempted to leave the testing of the nipype example out of this PR and trying to fix it in a separate one though I suspect this will be more efficiently tackled by solving other problems we have

so I would recommend commenting out this example from the doc for now so as to not confuse users